Laser-induced periodic surface structure on a polymer surface: The effect of a prerubbing treatment on the surface structure

The influence of the mechanical rubbing of a polyimide (PI) film on the laser-induced periodic structure (LIPS) was demonstrated. The periodicity and ampli- tude of LIPS were greater when the rubbing direction was parallel to the laser polar- ization direction. The amplitude became small and the periodicity of LIPS did not show an obvious change when the rubbing direction was perpendicular to the laser polariza- tion direction. The effect of the rubbing pretreatment on LIPS was explained on the basis of the wave-guide effect of rubbing-induced microgrooves on LIPS formation. The orientation of PI chains induced by mechanical rubbing was relaxed after laser irradi- ation, and a new orientation of PI chains was formed during the LIPS formation. When the rubbing direction was perpendicular to the laser polarization direction, the orien- tation of PI chains remained in the rubbing direction. The laser-irradiated, perpendic- ularly rubbed PI surface could be used to verify the effects of surface morphologies and intermolecular interactions on liquid-crystal alignment. © 2003 Wiley Periodicals, Inc. J